Summary

Below is an initial read-out of the key messages from TOTeM45:

Context:

• Global growth of gas-fired power generation as complement to renewables
• 23% of global 25,600 TWh from gas, 1.6% increase in 2017 (7.6% decrease in USA counterbalanced by 4.6% growth in rest of world – particularly China, EU, SE Asia)
• So why reluctance for GT research support?
• Challenges in terms of flexibility, transient response, etc.
• Currently no real driver for CCS on GTs from industry – carbon price too low, financial case?
• Combustion dynamics (CD) are a significant issue
• Dual-fuel (liquid/gas) flexible systems also required
• Different methods (e.g. axial) for ‘staged’ combustors, with strengths/weaknesses
• Different industrial staging designs e.g. EV Burner (Alstom) , SWOZZLE (GE)
• Swirl, vortex breakdown integral
• GT cycles increasing temperature for efficiency -> increased NOx?
• Near-term R&D priorities: Additive manufacture; model-based control (sensors, artificial intelligence, ‘big data’); enhanced prediction of CD

GTs for flexible power (operational and fuels flexibility):

• How far can we get with simplified lower-order network model + flame describing function (FDF) models for CD?
• Validation:  Encouraging/surprising!  (EM2C, Camb, Siemens, …) to date -> more experimental (optical) validation required
• Predictability sufficient for industry purposes?
• How to calculate FDFs ‘accurately enough’?
• Four-step chemistry sufficient (for industry?) – to be confirmed
• Active/feedback control?  Response time?
• New fuels (H2, NH3) will also suffer from CD
• Plea for industry to vocally support research funding applications in the field
• Problems in predicting CD, even when Wobbe Index (WI) is ‘in spec’, C2+?)  ->
• Additional combustion /fuel parameters required. What?  Methane Number?
• OEMs have developed control systems but they are expensive – cheaper options?
• Heading towards >20% H2 in gas grids.  Issues?
• New burners are now designed to avoid flashback
• ‘Permutation Entropy’ for predicting CD onset – 1s response
• Other ‘relatively cheap’ techniques, including laser-induced breakdown spectroscopy (LIBS) and chemiluminescence (CL), being developed for non-intrusive burner diagnostics – how much optical access practicable?

GTs for ‘storage-to-power’:

• H2 in gas system variety of sources (syngas/CCS, green H2,…)
• Changes required in combustion; materials/cooling; turbo
• WI variation insufficient: what in addition?
• New combustion systems required for high-H2 fuels?
• Promising ‘FLOX’ (flameless combustion) system claimed capable of burning H2 with high fuel/operational flexibility and low emissions
• What is and what isn’t FLOX?
• Staged combustion autoignition showed operational window for high-H2 operation
• H2 energy transportation -> case for ammonia (NH3)?
• Established challenges for NH3: economics ; NH3 emissions; NOx; public acceptance
• Various methods for reducing NOx recently demonstrated in Wales and Japan (RQL; humidified; operational pressures;..)
• Existing research tools enable ammonia combustion optimisation. Needs funding to keep UK competitive

GTs for safe, decarbonised power:

• Exhaust gas recirculation (EGR) required for post-combustion CO2 capture on GTs
• O2 will limit the degree of EGR achievable
• Oxyfuel CCS GT promising but need turbomachinery and combustor developments
• Oxyfuel with 1st generation burners shows good stability, but lots of challenges for development e.g. CO emissions
• Various ways of adapting GT operation for improving CCS efficiency.  But what is the optimum combination?
• Advanced solvents for post-combustion capture
• System integration and whole systems analysis required
• Social science, public perception, risk/safety for CCS
• H2 safety still requires attention: ignition, DDT potential, …
• How best to mitigate scenarios like flame-out, H2 jet in hot environment
• Are H2 explosion/detonation scaling sufficient?  Geometries?

Additive manufacturing and advanced materials:

• Considerable GT materials info, but often poorly characterised experimentally
• ‘Open Access’ materials database proposed (by ETN?): IFRF should link and promote
• Higher operating conditions …-> materials development needs
• Additive layer manufacturing (ALM) is a potential ‘game changer’
• ALM has key role for GTs in terms of enabling better thermal management and lightweighting
• Most OEMS have active ALM programmes
• ALM gives potential to design and manufacture high-temperature components which couldn’t be delivered with traditional techniques
• Enables reduction of materials utilised and significant incremental efficiency improvement mitigates/eliminates cost differential with traditional techniques
• Several examples of components built for high-end markets (e.g. F1, etc.) from likes of HEITA (eg. LT and HT HEXs, turbomachinery, fuel and combustion components
• Up to 50% weight reduction achieved.  Metal temperatures reduced by up to 220degC, enabling turbines to run hotter
• Could there be a role  as proposed  collective database for ALM future development?
• Expect to see considerable development in this field, challenges include surface finishing.